This invention relates to an object detecting device and method. This invention relates more particularly to an object detecting device conveniently usable on an automobile for detecting another vehicle and a method of using such a device.
There have been known laser radars of the type to be carried on a vehicle for transmitting a laser light beam in the direction of its motion, receiving its reflected waves to thereby detect a front-running vehicle and automatically outputting an alarm signal in order to prevent a collision. In order to prevent erroneous recognition of an object by such a detecting device due to the sloping of its detection area caused by errors in the attachment of the laser radar onto the vehicle or the condition of setting on the vehicle, Japanese Patent Publication Tokkai 2000-56020 has disclosed a method of transmitting laser light widely spreading in the vertical direction firstly in a first direction and secondly at a different time in a second direction which is farther upward from the first direction and adjusting the vertical direction of the optical axis of the laser light such that the received reflected waves have the same intensity. This method requires a plurality of laser diodes because laser light must be transmitted in different vertical directions and the structure of the laser radar becomes complex. Since use is made of laser light which spreads widely in the vertical direction, furthermore, there is a high probability of misjudging the road or overpasses and road signs disposed over the road as a vehicle. Still another problem of this prior art technology was that no correction could be made in the absence of an object of detection.